An East-West switching transistor is coupled between a flyback transformer primary winding and a horizontal deflection output transistor circuit to control retrace energy to obtain an East-West modulation of the deflection current amplitude as required for East-West pincushion raster correction. A pair of series coupled first and second capacitors forming a capacitive voltage divider are coupled to a retrace resonant circuit that includes the deflection winding via a sampling switch, during a first half of a retrace interval, to produce a first ramping capacitor voltage in the first capacitor from a portion of a retrace pulse voltage. The first capacitor is coupled to an East-West pincushion raster correction current for producing a second ramping capacitor voltage in the first capacitor that ramps in an opposite direction. A comparator is responsive to the capacitor voltage for controlling a conduction interval of the East-West switching transistor.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A projection television, comprising: a plurality of image projectors for respective images of different colors; a projection screen formed by superimposing linear Fresnel lenses having mutually perpendicular optical active axes and a three-dimensional hologram forming a lenticular lens, said screen receiving images from said projectors on a first side and displaying said images on a second side with controlled light dispersion of said displayed images; and, said screen forming an interference array with optical properties varying differently from one another horizontally and vertically across a field of view due to said mutually perpendicular optical active axes of said linear Fresnel lenses, said optical properties varying in at least one of holographic gain, collimation and centering, wherein the hologram and the Fresnel lenses have optical properties that vary between a center point of the superimposed Fresnel lenses and edges of the screen.
2. The projection television of claim 1 , wherein the center point of the superimposed Fresnel lenses corresponds with a center of the screen.
3. The projection television of claim 1 , wherein the center point of the superimposed Fresnel lenses is displaced vertically from the center of the screen.
4. The projection television of claim 1 , wherein the optical properties of the hologram and the Fresnel lenses vary differently from one another between the center of the superimposed Fresnel lenses and the edges of the screen.
5. The projection television of claim 1 , wherein the Fresnel lenses are centered horizontally and displaced vertically with respect to the center of the screen.
6. The projection television of claim 1 , wherein the hologram has an increasing gain proceeding from the center point of the hologram toward the edges.
7. The projection television of claim 6 , wherein the gain varies between approximately 14.8 at the center point and 22.5 at least at the edges in one of a vertical and a horizontal plane.
8. The projection television of claim 6 , wherein the gain varies from the center point toward the edges in a pattern corresponding to an aspect ratio of the screen.
9. The projection television of claim 6 , wherein the center point corresponds to a center of the screen.
10. The projection television of claim 6 , wherein the center point is displaced vertically from a center of the screen.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 12, 1999
August 20, 2002
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